Abstract

Differential irrigation treatments were applied to Chenin blanc grapevines during 1959 and 1960. Three different irrigation treatments were applied. The driest treatment received no irrigation while the wettest treatment received 3 irrigations in 1959 and 4 irrigations in 1960 between late May and early August. Measurements made throughout the season include soil moisture depletion, water use, shoot elongation, berry growth, total soluble solids and total acidity of berries, and petiole analysis. Other measurements made are weight of prunings, trunk diameter, carbohydrate levels of canes during the winter and complete must and wine analyses including tasting tests. The results are presented. Significant differences were observed between treatments in yield, berry growth, shoot elongation, the weight of pruning and potassium levels in petioles at harvest. There was a tendency for sugars to be lower and acid higher in the wetter treatments at a given time during the season. No significant differences were observed in tasting scores of the wines despite significant differences between wines in pH, color and volatile acid. Shoot elongation was most sensitive to water deficits and shows promise as a criterion for timing irrigations. The experiments are being continued.